1. Field of the Invention
The present invention relates generally to a method and apparatus for plating thin films and, more particularly, plating metal films to form interconnects in semiconductor devices.
2. Description of the Prior Art
As semiconductor device features continue to shrink according to Moore""s law, interconnect delay is larger than device gate delay for 0.18 xcexcm generation devices if aluminum (Al) and SiO2 are still being used. In order to reduce the interconnect delay, copper and low k dielectric are a possible solution. Copper/low k interconnects provide several advantages over traditional Al/SiO2 approaches, including the ability to significantly reduce the interconnect delay, while also reducing the number of levels of metal required, minimizing power dissipation and reducing manufacturing costs. Copper offers improved reliability in that its resistance to electromigration is much better than aluminum. A variety of techniques have been developed to deposit copper, ranging from traditional physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques to new electroplating methods. PVD Cu deposition typically has a cusping problem which results in voids when filling small gaps ( less than 0.18 xcexcm) with a large aspect ratio. CVD Cu has high impurity incorporated inside the film during deposition, which needs a high temperature annealing to drive out the impurity in order to obtain a low resistivity Cu film. Only electroplated Cu can provide both low resistivity and excellent gap filling capability at the same time. Another important factor is the cost; the cost of electroplating tools is two thirds or half of that of PVD or CVD tools, respectively. Also, low process temperatures (30xc2x0 to 60xc2x0 C.) for electroplating Cu are advantageous with low k dielectrics (polymer, xerogels and aerogels) in succeeding generations of devices.
Electroplated Cu has been used in printed circuit boards, bump plating in chip packages and magnetic heads for many years. In conventional plating machines, density of plating current flow to the periphery of wafers is greater than that to the center of wafers. This causes a higher plating rate at the periphery than at the center of wafers. U.S. Pat. No. 4,304,841 to Grandia et al. discloses a diffuser being put between a substrate and an anode in order to obtain uniform plating current flow and electrolyte flow to the substrate. U.S. Pat. No. 5,443,707 to Mori discloses manipulating plating current by shrinking the size of the anode. U.S. Pat. No. 5,421,987 to Tzanavaras discloses a rotating anode with multiple jet nozzles to obtain a uniform and high plating rate. U.S. Pat. No. 5,670,034 to Lowery discloses a transversely reciprocating anode in front of a rotating wafer to improve plating thickness uniformity. U.S. Pat. No. 5,820,581 to Ang discloses a thief ring powered by a separate power supply to manipulate the plating current distribution across the wafer.
All of these prior art approaches need a Cu seed layer prior to the Cu plating. Usually the Cu seed layer is on the top of a diffusion barrier. This Cu seed layer is deposited either by physical vapor deposition (PVD), or chemical vapor deposition (CVD). As mentioned before, however, PVD Cu typically has a cusping problem, which results in voids when filling small gaps ( less than 0.18 xcexcm) with a large aspect ratio with subsequent Cu electroplating. CVD Cu has high impurity levels incorporated in the film during deposition, requiring a high temperature annealing to drive out the impurities in order to obtain a low resistivity Cu seed layer. As device feature size shrinks this Cu seed layer will become a more serious problem. Also, deposition of a Cu seed layer adds an additional process, which increases IC fabrication cost.
Another disadvantage of the prior art is that the plating current and electrolyte flow pattern are manipulated dependently, or only the plating current is manipulated. This limits the process turning window, because the optimum plating current condition does not necessarily synchronize with optimum electrolyte flow condition for obtaining excellent gap filling capability, thickness uniformity and electrical uniformity as well as grain size and structure uniformity all at the same time.
Another disadvantage of the prior art is that plating head or plating systems are bulky with large foot prints, which causes higher cost of ownership for users.
It is an object of the invention to provide a novel method and apparatus for plating a metal film directly on a barrier layer without using a seed layer produced by a process other than plating.
It is a further object of the invention to provide a novel method and apparatus for plating a metal film over a thinner seed layer than employed in the prior art.
It is an additional object of the invention to provide a novel method and apparatus for plating a thin film with a more uniform thickness across a wafer.
It is a further object of the invention to provide a novel method and apparatus for plating a conducting film with a more uniform electrical conductivity across a wafer.
It is a further object of the invention to provide a novel method and apparatus for plating a thin film with a more uniform film structure, grain size, texture and orientation.
It is a further object of the invention to provide a novel method and apparatus for plating a thin film with an improved gap filling capability across a wafer.
It is a further object of the invention to provide a novel method and apparatus for plating a metal film for interconnects in an integrated circuit IC chip.
It is a further object of the invention to provide a novel method and apparatus for plating a thin film, with the method and apparatus having independent plating current control and electrolyte flow pattern control.
It is a further object of the invention to provide a novel method and apparatus for plating a metal thin film for a damascene process.
It is a further object of the invention to provide a novel method and apparatus for plating a metal film with a low impurity level.
It is a further object of the invention to provide a novel method and apparatus for plating copper with a low stress and good adhesion.
It is a further object of the invention to provide a novel method and apparatus for plating a metal film with a low addled particle density.
It is a further object of the invention to provide a novel plating system with a small footprint.
It is a further object of the invention to provide a novel plating system with a low cost of ownership.
It is a further object of the invention to provide a novel plating system which plates a single wafer at a time.
It is a further object of the invention to provide a novel plating system with an in-situ film thickness uniformity monitor.
It is a further object of the invention to provide a novel plating system with a built-in cleaning system with wafer dry-in and dry-out.
It is a further object of the invention to provide a novel plating system with a high wafer throughput.
It is a further object of the invention to provide a novel plating system which can handle a wafer size beyond 300 mm.
It is a further object of the invention to provide a novel plating system with multiple plating baths and cleaning/drying chambers.
It is a further object of the invention to provide a novel plating system with a stacked plating chamber and cleaning/dry chamber structure.
It is a further object of the invention to provide a novel plating system with automation features of the Standard Mechanical Interface (SMIF), the Automated Guided Vehicle (AGV), and the SEMI Equipment (Communication Standard/Generic Equipment Machine (SECS/GEM).
It is a further object of the invention to provide a novel plating system meeting Semiconductor Equipment and Materials International (SEMI) and European safety specifications.
It is a further object of the invention to provide a novel plating system with high productivity having a large mean time between failures (MTBF), small scheduled down time, and large equipment uptime.
It is a further object of the invention to provide a novel plating system controlled by a personal computer with a standard operating system, such as an IBM PC under a Windows NT environment.
It is a further object of the invention to provide a novel plating system with a graphical user interface, such as a touch screen.
These and related objects and advantages of the invention may be achieved through use of the novel method and apparatus herein disclosed. A method for plating a film to a desired thickness on a surface of a substrate in accordance with the invention includes plating the film to the desired thickness on a first portion of the substrate surface. The film is then plated to the desired thickness on at least a second portion of the substrate to give a continuous film at the desired thickness on the substrate. Additional portions of the substrate surface adjacent to and contacting the film already plated on one or more of the previous portions are plated as necessary to give a continuous film over the entire surface of the substrate.
An apparatus for plating a film on a substrate in accordance with the invention includes a substrate holder for positioning the substrate for contact with a plating electrolyte. The apparatus has at least one anode for supplying plating current to the substrate and at least two flow controllers connected to supply electrolyte contacting the substrate. At least one control system is coupled to the at least one anode and the at least two flow controllers to provide electrolyte and plating current in combination to successive portions of the substrate to provide a continuous, uniform thickness film on the substrate by successive plating of the film on the portions of the substrate.
In another aspect of the invention, an apparatus for plating a film on a substrate in accordance with the invention includes a substrate holder for positioning the substrate for contact with a plating electrolyte. The apparatus has at least two anodes for supplying plating current to the substrate and at least one flow controller connected to supply electrolyte contacting the substrate. At least one control system is coupled to the at least two anode and the at least one flow controller to provide electrolyte and plating current in combination to successive portions of the substrate to provide a continuous, uniform thickness film on the substrate by successive plating of the film on the portions of the substrate.
In a further aspect of the invention, an apparatus for plating a film on a substrate in accordance with the invention includes a substrate holder for positioning the substrate for contact with a plating electrolyte. The apparatus has at least one anode for supplying plating current to the substrate and at least one flow controller connected to supply electrolyte contacting the substrate. The at least one flow controller comprises at least three cylindrical walls, a first of the cylindrical walls positioned under a center portion of the substrate extending upward closer to the substrate than a second one of the cylindrical walls positioned under a second portion of the substrate peripheral to the center portion. A drive mechanism is coupled to the substrate holder to drive the substrate holder up and down to control one or more portions of the substrate contacting the electrolyte. At least one control system is coupled to the at least one anode and the at least one flow controller to provide electrolyte and plating current in combination to successive portions of the substrate to provide a continuous, uniform thickness film on the substrate by successive plating of the film on the portions of the substrate.
In yet another aspect of the invention, an apparatus for plating a film on a substrate in accordance with the invention includes a substrate holder for positioning the substrate for contact with a plating electrolyte. The apparatus has at least one anode for supplying plating current to the substrate and at least one flow controller connected to supply electrolyte contacting the substrate. The at least one flow controller comprises at least three cylindrical walls movable upward toward the substrate and downward away from the substrate, to adjust a gap between the substrate and each of the cylindrical walls to control one or more portions of the substrate contacting the electrolyte. A drive mechanism is coupled to the substrate holder to drive the substrate holder up and down to control one or more portions of the substrate contacting the electrolyte. At least one control system is coupled to the at least one anode and the at least one flow controller to provide electrolyte and plating current in combination to successive portions of the substrate to provide a continuous, uniform thickness film on the substrate by successive plating of the film on the portions of the substrate.
In still another aspect of the invention, an apparatus for plating a film on a substrate, includes a substrate holder for positioning the substrate in a body of electrolyte. At least one movable jet anode supplies plating current and electrolyte to the substrate. The movable jet anode is movable in a direction parallel to the substrate surface. A flow controller controls electrolyte flowing through the movable jet anode. At least one control system is coupled to the movable jet anode and the flow controller to provide electrolyte and plating current in combination to successive portions of the substrate to provide a continuous, uniform thickness film on the substrate by successive plating of the film on the portions of the substrate.
In a still further aspect of the invention, an apparatus for plating a film on a substrate includes a substrate holder for positioning the substrate above an electrolyte surface. A first drive mechanism is coupled to the substrate holder to move the substrate holder toward and away from the electrolyte surface to control a portion of a surface of the substrate contacting the electrolyte. A bath for the electrolyte has at least one anode mounted in the bath. A second drive mechanism is coupled to the bath to rotate the bath around a vertical axis to form a substantially parabolic shape of the electrolyte surface. A control system is coupled to the first and second drive mechanisms and to the at least one anode to provide electrolyte and plating current in combination to successive portions of the substrate to provide a continuous, uniform thickness film on the substrate by successive plating of the film on the portions of the substrate.
In yet another aspect of the invention, an apparatus for plating a film on a substrate includes a substrate holder for positioning the substrate above an electrolyte surface. A first drive mechanism is coupled to the substrate holder to move the substrate holder toward and away from the electrolyte surface to control a portion of a surface of the substrate contacting the electrolyte. A second drive mechanism is coupled to the substrate holder to rotate the substrate holder around an axis vertical to the surface of the substrate. A third drive mechanism is coupled to the substrate holder to tilt the substrate holder with respect to the electrolyte surface. A bath for the electrolyte has at least one anode mounted in the bath. A control system is coupled to the first, second and third drive mechanisms and to the at least one anode to provide electrolyte and plating current in combination to successive portions of the substrate to provide a continuous, uniform thickness film on the substrate by successive plating of the film on the portions of the substrate.
In a still further aspect of the invention, a method for plating a film to a desired thickness on a surface of a substrate includes providing a plurality of stacked plating modules and a substrate transferring mechanism. A substrate substrate is picked from a substrate holder with the substrate transferring mechanism. The substrate is loaded into a first one of stacked plating modules with the substrate transferring mechanism. A film is plated on the substrate in the first the one of the stacked plating modules. The substrate is returned to the substrate holder with the substrate transferring mechanism.
In another aspect of the invention, an automated tool for plating a film on a substrate includes at least two plating baths positioned in a stacked relationship, at least one substrate holder and a substrate transferring mechanism. A frame supports the plating baths, the substrate holder and the substrate transferring mechanism. A control system is coupled to the substrate transferring mechanism, substrate holder and the plating baths to continuously perform uniform film deposition on a plurality of the substrates.
Method 1: Portion of Wafer Surface is Contacted with Electrolyte (Static Anode)
The above and other objects of the invention are further accomplished by a method for plating a thin film directly on substrate with a barrier layer on top, comprising: 1) flowing electrolyte on a portion of a substrate surface with a barrier layer on the top; and 2) turning on DC or pulse power to plate metal film on the same portion area of substrate until the film thickness reaches the pre-set value; 3) repeating step 1 and 2 for additional portions of the substrate by flowing electrolyte to the same additional portion of substrate; 4) repeating step 3 until the entire substrate surface is plated with a thin seed layer; 5) flowing electrolyte to entire area of the substrate; 6) supplying power to apply positive potential to all anodes to plate the thin film until the film thickness reaches a desired thickness value.
Method 2: Whole Wafer Surface is Contacted by Electrolyte (Static Anodes)
In a further aspect of the invention there is provided another method for plating a thin film directly on a substrate with a barrier layer on top, comprising: 1) flowing electrolyte on the full surface of the substrate; 2) plating the thin film only on a portion of the substrate surface by applying positive potential on an anode close to the same portion of wafer surface and by applying negative potential on all other anodes close to the remainder of the substrate surface until the plated film thickness on the same portion of the substrate reaches a pre-set value; 3) repeating step 2 for an additional portion of the substrate; 4) repeating step 3 until the whole area of substrate is plated with a thin seed layer; 5) plating a thin film on the whole area of the substrate at the same time by applying positive potential to all anodes until the thickness of the film on the whole surface of the substrate reaches a pre-set thickness value.
Method 3: Whole Wafer Surface is Contacted by Electrolyte at Beginning, and then Portion of Wafer which has been Plated is Moved Out of Electrolyte
In a farther aspect of the invention there is provided another method for plating a thin film directly on a substrate with a barrier layer on top, comprising: 1) flowing electrolyte on the full surface of a substrate; 2) plating the thin film only on a portion of the substrate surface by applying positive potential on an anode close to the same portion of the substrate surface and by applying negative potential on all other anodes close to the remainder of the substrate surface until the plated film thickness on the portion of the substrate surface reaches a pre-set value; 3) move the electrolyte only out of contact with the all plated portion of the substrate and keep the electrolyte still touching the rest of the non-plated portion of the substrate; 4) repeat steps 2 and 3 for plating the next portion of the substrate; 5) repeat step 4 until the whole area of the substrate is plated with a thin seed layer; 6) plate a thin film on the whole substrate at the same time by applying positive potential to all anodes and flowing electrolyte on the whole surface of the substrate until the thickness of the film on the whole surface of the substrate reaches a pre-set thickness value.
Method 4: A Portion of Substrate is Contacted by Electrolyte at Beginning and then both Plated Portion and the Next Portion of the Substrate are Contacted by Electrolyte
In a further aspect of the invention there is provided another method for plating a thin film directly on a substrate with a barrier layer on top, comprising: 1) flowing electrolyte on a first portion of the substrate surface; and 2) plating the thin film only on the first portion of the substrate surface by applying positive potential on an anode close to the first portion of the substrate surface until the plated film thickness on the first portion of the substrate reaches a pre-set value; 3) moving the electrolyte to contact a second portion of the substrate surface and at the same time keep the electrolyte still contacting the first portion of the substrate surface; 4) plating the thin film only on the second portion of the substrate surface by applying positive potential on a anode close to the second portion of the substrate surface and applying a negative potential on an anode close to the first portion of the substrate surface; 5) repeating step 3 and 4 for plating a third portion of the substrate surface; 6) repeating step 4 until the whole area of the substrate surface is plated with a thin seed layer; 7) plating the thin film on the whole wafer at the same time by applying positive potential to all anodes and flowing electrolyte on the full surface of the substrate until the thickness of the film on the whole surface of the substrate reaches a pre-set thickness value.
Method 5: Portion of Substrate Surface is Contacted with Electrolyte (Movable Anodes) for Seed Layer Plating Only
In a further aspect of the invention there is provided another method for plating a thin film directly on a substrate with a barrier layer on top, comprising: 1) flowing electrolyte on a portion of the substrate surface with a barrier layer on the top through a movable jet anode; 2) turning on DC or pulse power to plate a metal film on the portion of the substrate until the film :thickness reaches a pre-set value; 3) repeating steps 1 and 2 for an additional portion of the substrate by moving the movable jet anode close to the additional portion of the substrate; 4) repeating step 3 until the whole area of the substrate is plated with a thin seed layer.
Method 6: Whole Substrate Surface is Contacted by Electrolyte (Movable Anodes) for Seed Layer Plating Only
In a further aspect of the invention there is provided another method for plating a thin film directly on a substrate with a barrier layer on top, comprising: 1) immersing the full surface of a substrate into an electrolyte; 2) plating the thin film only on a first portion of the substrate surface by applying positive potential on a movable anode close to the first portion of the substrate surface; 3) repeating step 2 for additional portions of the substrate by moving the movable anode close to the additional portions of the substrate; 4) repeating step 3 until the whole area of the substrate is plated with a thin seed layer.
Apparatus 1: Multiple Liquid Flow Mass Controllers (LMFCs) and Multiple Power Supplies
In a further aspect of the invention there is provided an apparatus for plating a thin film directly on a substrate with a barrier layer on top, comprising: a substrate holder for holding a substrate above an electrolyte surface; at least two anodes, with each anode being separated by an insulating cylindrical wall; a separate liquid mass flow controller for controlling electrolyte flowing through a space between the two cylindrical walls to touch a portion of the substrate; a separate power supply to create a potential between each anode and cathode or the substrate; the portion of the substrate surface will be plated only when the liquid flow controller and power supply corresponding to the portion of the substrate is turned on at the same time.
Apparatus 2: One Common LMFC and Multiple Power Supplies
In a further aspect of the invention there is provided another apparatus for plating a thin film directly on a substrate with a barrier layer on top, comprising: a substrate chuck holding the substrate above an electrolyte surface; a motor driving the substrate holder up or down to control the portion of the surface area contacting the electrolyte; at least two anodes, with each anode being separated by two insulating cylindrical walls, the height of the cylindrical walls being reduced along the outward radial direction of the substrate; one common liquid mass flow controller for controlling electrolyte flowing through spaces between each adjacent cylindrical wall to reach the substrate surface; separate power supplies to create potential between each anode and cathode or the substrate; a portion of the substrate surface is plated only when the anode close to the portion of the substrate is powered to positive potential and the rest of anodes are powered to negative potential and the portion of the substrate is contacted by the electrolyte at the same time. After the plating thickness reaches a seed layer set-value, the substrate is moved up so that the plated portion is out of the electrolyte. This will allow no further plating or etching when other portions of the substrate are plated.
Apparatus 3: Multiple LMFCs and One Common Power Supply
In a further aspect of the invention there is provided another apparatus for plating a thin film directly on a substrate with a barrier layer on top, comprising: a substrate holder holding the substrate above an electrolyte surface; at least two anodes, each anode being separated by two insulating cylindrical walls; a separate liquid mass flow controller for controlling electrolyte flowing through a space between the two cylindrical walls to touch a portion of the substrate; one common power supply to create potential between each anode and cathode or the substrate; a portion of the substrate surface is plated only when its liquid mass flow controller and the power supply are turned on at the same time.
Apparatus 4: One Common LMFC and One Common Power Supply
In a further aspect of the invention there is provided another apparatus for plating a thin film directly on a substrate with a barrier layer on top, comprising: a substrate holder holding the substrate above an electrolyte surface; at least two anodes, each anode being separated by two insulating cylindrical walls; the cylindrical walls can be moved up and down to adjust a gap between the substrate and the top of the cylindrical walls, thereby to control electrolyte to contact a portion of the substrate adjacent to the walls, one liquid mass flow controller for controlling electrolyte flowing through a space between the two cylindrical walls; one power supply to create potential between all anodes and a cathode or the substrate; a portion of the substrate surface will be plated only when the cylindrical wall below the portion of the substrate surface is moved up so that the electrolyte touches the portion of the substrate and the power supply is turned on at the same time.
Apparatus 5: Movable Anode with Substrate not Immersed in Electrolyte
In a further aspect of the invention there is provided another apparatus for plating a thin film directly on a substrate with a barrier layer on top, comprising: a substrate holder for holding the substrate above an electrolyte surface; a movable anode jet placed under and close to the substrate, the movable anode jet being capable of moving toward the substrate surface, thereby the electrolyte from the anode jet can be controlled to touch any portion of the substrate; one power supply to create a potential between the movable anode jet and a cathode or the substrate; a portion of substrate surface is plated only when the portion of the surface is contacted by electrolyte ejected from the movable anode jet.
Apparatus 6: Movable Anode with Substrate Immersed in Electrolyte
In a further aspect of the invention there is provided another apparatus for plating a thin film directly on a substrate with a barrier layer on top, comprising: a substrate holder for holding a substrate, with the substrate being immersed in electrolyte; a movable anode jet adjacent to the substrate, the movable anode jet being movable toward the substrate surface, whereby the plating current from the anode jet can be controlled to go to any portion of the substrate; one power supply to create potential between the movable anode jet and a cathode or the substrate; a portion of substrate surface is plated only when the portion of the substrate is close to the movable anode jet.
Method 7: Plating Metal Film on to Substrate through a Fully Automation Plating Tool
In a further aspect of the invention there is provided another method for plating a thin film onto a substrate through a fully automated plating tool, comprising: 1) picking up a wafer from a cassette and sending to one of stacked plating baths with a robot; 2) plating metal film on the wafer; 3) after finishing the plating, picking up the plated wafer from the stacked plating bath with the robot and transporting it to one of the stacked cleaning/drying chambers; 4) Cleaning the plated wafer; 5) drying the plated wafer; 6) picking up the dried wafer from the stacked cleaning/drying chamber with the robot and transporting it to the cassette.
Apparatus 7: Fully Automated Tool for Plating Metal Film on to Substrate
In a further aspect of the invention there is provided a fully automated tool for plating a metal film onto a substrate, comprising: a robot transporting a wafer; wafer cassettes; multiple stacked plating baths; multiple stacked cleaning/drying baths; an electrolyte tank; and a plumbing box holding a control valve, filter, liquid mass flowing controller, and plumbing. The fully automated tool further comprises a computer and control hardware coupled between the computer and the other elements of the automated tool, and an operating system control software package resident on the computer.
Method 8: Plating Thin Layerxe2x80x94Portion of Wafer Surface is Contacted with Electrolyte, and then both Plated Portion and the next Portion of Wafer are Contacted by Electrolyte and are Plated by Metal
In a further aspect of the invention there is provided another method for plating a thin film directly on a substrate with a barrier layer or thin seed layer on top, comprising: 1) turning on DC or pulse power; 2) making a first portion of the substrate surface contact an electrolyte, so that a metal film is plated on the first portion of the substrate; 3) when the metal film thickness reaches a pre-set value, repeating step 1 and 2 for one or more additional portions of the substrate by making the one or more additional portions of the substrate contact the electrolyte, while continuing to plate the first portion of the substrate and any previous of the one or more additional portions of the substrate; 4) repeating step 3 until the entire area of the substrate is plated with a thin seed layer.
Method 9: Plating Thin Layer then Thick Layerxe2x80x94Portion of Wafer Surface is Contacted with Electrolyte, and then both Plated Portion and the Next Portion of Wafer are Contacted by Electrolyte and are Plated by Metal
In a further aspect of the invention there is provided another method for plating a film directly on substrate with a barrier layer or thin seed layer on top, comprising: 1) turning on DC or pulse power, 2) making a first portion of a substrate surface contact an electrolyte, so that a metal film is plated on the first portion of the substrate; 3) when the metal film thickness reaches a pre-set value, repeating step 1 and 2 for one or more additional portions of the substrate by making the one or more additional portions of the substrate contact the electrolyte, while continuing to plate the first portion of the substrate and any previous of the one or more additional portions of the substrate; 4) repeating step 3 until all portions of the substrate are plated with a thin seed layer; 5) contacting all of the portions of the substrate with the electrolyte; 6) applying positive potential to anodes adjacent to all of the portions of the substrate to plate a film until the film thickness reaches a desired thickness value.
Method 10: Plating a Thin Layerxe2x80x94A First Portion of Wafer Surface is Contacted by Electrolyte Initially, and then Both the First Portion and a Second Portion of Wafer are Contacted by Electrolyte, but Only the Second Portion of Wafer is Plated
In a further aspect of the invention there is provided another method for plating a film directly on substrate with a barrier layer or thin seed layer on top, comprising: 1) applying a positive potential on a first anode close to a first portion of the substrate surface; 2) contacting the first portion of the substrate surface with the electrolyte, so that the film is plated on the first portion of the substrate surface; 3) when the film thickness on the first portion of the substrate surface reaches a pre-set value, further contacting a second portion of the substrate surface while maintaining electrolyte contact with the first portion of the substrate surface; 4) plating the film only on the second portion of the substrate surface by applying positive potential on a second anode close to the second portion of the substrate surface and applying a sufficient positive potential on the first anode close to the first portion of the substrate surface so that the first portion of the substrate surface is not plated but also not deplated; 5) repeating steps 3 and 4 for plating a third portion of the substrate while avoiding deplating of the first and second portions of the substrate surface; 6) repeating step 4 for successive areas of the substrate surface until whole area of the substrate surface is plated with a thin seed layer.
Method 11: Plating Thin Layer then Thick Layerxe2x80x94A Portion of Wafer is Contacted by Electrolyte at Beginning and then both Plated Portion and the Next Portion of Wafer are Contacted by Electrolyte, and Only the Next Portion of Wafer is Plated
In a further aspect of the invention there is provided another method for plating a film directly on substrate with a barrier layer or thin seed layer on top, comprising: 1) contacting a first portion of a substrate area with an electrolyte; and 2) plating thin film only on the first portion of the substrate surface by applying positive potential on a first anode close to the same portion of wafer surface until a plated film thickness on the first portion of the substrate surface reaches a pre-set value; 3) further contacting a second portion of the substrate surface while maintaining electrolyte contact with the first portion of the substrate surface; 4) plating the film only on the second portion of the substrate surface by applying positive potential on a second anode close to the second portion of the substrate surface and applying a sufficient positive potential on the first anode close to the first portion of the substrate surface so that the first portion of the substrate surface is not plated but also not deplated; 5) repeating steps 3 and 4 for plating a third portion of the substrate while avoiding deplating of the first and second portions of the substrate surface; 6) repeating step 4 until whole area of the substrate surface is plated with a thin seed layer; 7) plating a further metal film on the whole wafer at the same time by applying positive potential to all anodes and contacting the whole area of the substrate surface until a thickness of the further film on the whole substrate surface reaches a desired thickness value.
Apparatus 8: Rotating Plating Bath to Form Parabolic Shape of Electrolyte (Single-anode)
In a further aspect of the invention there is provided another apparatus for plating a film directly on a substrate with a barrier layer or thin seed layer on top, comprising: a substrate chuck holding the substrate above an electrolyte surface; a motor driving the substrate holder up or down to control the portion of the surface area contacting the electrolyte; a bath with an anode immersed; a liquid mass flow controller for controlling electrolyte flowing to contact the substrate; a power source to create potential between the anode and a cathode or substrate; another motor driving the plating bath to rotate around its central axis at such a speed that a surface of the electrolyte surface forms a parabolic shape; a portion of the substrate surface is plated only when the liquid mass flow controller and the power supply are turned on at the same time. After a plating thickness reaches a seed layer predetermined value, the substrate is moved down so that the next portion of the substrate is contacting the electrolyte and is plated.
Apparatus 9: Rotating Plating Bath to Form Parabolic Shape of Electrolyte (Multi-anodes)
In a further aspect of the invention there is provided another apparatus for plating a film directly on a substrate with a barrier layer or thin seed layer on top, comprising: a substrate chuck holding the substrate above an electrolyte surface; a motor driving the substrate holder up or down to control the portion of the surface area contacting the electrolyte; at least two anodes, each anode being separated by two insulating cylindrical walls; a separate liquid mass flow controller for controlling electrolyte flowing through a space between the two cylindrical walls to contact a portion of the substrate; separate power supplies to create potential between each anode and cathode or the substrate; another motor driving the plating bath to rotate around its central axis at such a speed that a surface of the electrolyte surface forms a parabolic shape; a portion of the substrate surface will be plated only when the anode close to that portion of the substrate is powered to positive as well as that portion of the substrate surface is contacted by electrolyte at the same time. After a plating thickness reaches a predetermined value, the substrate is moved down so that the next portion of the substrate is contacting the electrolyte and is plated.
Apparatus 10: Tilting Wafer Holder Around y-axis or x-axis (Single-anode)
In a further aspect of the invention there is provided another apparatus for plating a film directly on a substrate with a barrier layer or thin seed layer on top, comprising: a substrate chuck holding the substrate above an electrolyte surface, the substrate holder being rotatable around a z-axis, and also tiltable around a y-axis or an x-axis; an anode; a liquid mass flow controller for controlling the electrolyte to contact the substrate; a power source to create potential between the anode and a cathode or substrate; a peripheral portion of the substrate surface will be plated only when the substrate chuck is tilted around the y-axis or x-axis and is rotated around the z-axis so that the peripheral portion of the substrate is contacted by electrolyte, and the liquid mass flow controller and power source are turned on at the same time.
Apparatus 11: Tilting Rotation Axis of Wafer Holder (Multi-anodes)
In a further aspect of the invention there is provided another apparatus for plating a film directly on a substrate with a barrier layer or thin seed layer on top, comprising: a substrate chuck holding the substrate above an electrolyte surface, the substrate holder being rotatable around a z-axis, and also tiltable around a y-axis or an x-axis; at least two anodes, each anode being separated by two insulating cylindrical walls; a separate liquid mass flow controller for controlling electrolyte flowing through a space between the two cylindrical walls to contact a portion of the substrate; separate power supplies to create potential between each anode and cathode or the substrate; a peripheral portion of the substrate surface will be plated only when the substrate chuck is tilted around the y-axis or x-axis and is rotated around the z-axis so that the peripheral portion of the substrate is contacted by electrolyte, and the liquid mass flow controllers and power source are turned on at the same time.
Apparatus 12: Rotating Plating Bath to Form Parabolic Shape of Electrolyte and Tilting Wafer Holder Around y-axis or x-axis (Single-anode)
In a further aspect of the invention there is provided another apparatus for plating a film directly on a substrate with a barrier layer or thin seed layer on top, comprising: a substrate chuck holding the substrate above an electrolyte surface; a motor driving the substrate holder up or down to control the portion of the surface area contacting the electrolyte; the substrate holder being rotatable around a z-axis, and also tiltable around a y-axis or an x-axis; an anode; a liquid mass flow controller for controlling the electrolyte to contact the substrate; a power source to create potential between the anode and a cathode or substrate; another motor driving the plating bath to rotate around its central axis at such a speed that a surface of the electrolyte surface forms a parabolic shape; a peripheral portion of the substrate surface will be plated only when the substrate chuck is tilted around the y-axis or x-axis and is rotated around the z-axis so that the peripheral portion of the substrate is contacted by electrolyte, and the liquid mass flow controller and power source are turned on at the same time.
Apparatus 13: Rotating Plating Bath to Form Parabolic Shape of Electrolyte and Tilting Wafer Holder Around y-axis or x-axis (Multi-anodes)
In a further aspect of the invention there is provided another apparatus for plating a film directly on a substrate with a barrier layer or thin seed layer on top, comprising: a substrate chuck holding the substrate above an electrolyte surface; a motor driving the substrate holder up or down to control the portion of the surface area contacting the electrolyte; the substrate holder being rotatable around a z-axis, and also tiltable around a y-axis or an x-axis; at least two anodes, each anode being separated by two insulating cylindrical walls, the cylindrical walls being closer to the substrate at its center than at its edge; a separate liquid mass flow controller for controlling electrolyte flowing through a space between the two cylindrical walls to contact a portion of the substrate; separate power supplies to create potential between each anode and cathode or the substrate; another motor driving the plating bath to rotate around its central axis at such a speed that a surface of the electrolyte surface forms a parabolic shape; a portion of the substrate surface will be plated only when the anode close to that portion of the substrate is powered to positive as well as that portion of the substrate surface being contacted by electrolyte at the same time. After a plating thickness reaches a predetermined value, the substrate is moved down so that the next portion of the substrate is contacted by the electrolyte and is plated.
The central idea of this invention for plating a metal film without using a seed layer produced by a process other than plating is to plate one portion of wafer a time to reduce current load to a barrier layer, since the barrier layer typically has 100 times higher resistivity than a copper metal film. For details, please see following theoretical analysis.
The attainment of the foregoing and related objects, advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention, taken together with the drawings, in which: